No one wants to lose newborn calves, but a reasonable goal is to maintain this loss at less than 3 to 5% in the first month of their lives. Research has shown that 52% of those calves that do die are lost to diarrhea and 21% due to respiratory disease, most often to secondary pneumonia after an initial bout of scours.
Our usual focus with young calves is prevention of enteric disease. A definitive diagnosis of the cause of all scours cases should be made but some generalizations can be made by age of the calf. The most common cause of scours, up to 5 days old, is enterotoxigenic E. coli. 90% of these positive cases are from the K99 pilus adhesion antigen. All organisms that cause diarrhea require attachment to intestinal cells. The attachment sites for K99 E. coli disappears at 72 hours of age. In most cases scours after day 5 are caused by some other pathogen. This loss of attachment sites is unique to E. coli. Nonenterotoxigenic E. coli can also cause systemic disease manifesting as encephalitis, respiratory or enteric disease. However, when colostrum is properly managed this is of minimal concern.
Diarrhea at 7 to 10 days of age is often caused by rotavirus, with coronavirus causing scours at 7 to 15 days. Rotavirus is the more common of the two and thankfully, less severe. Calves can develop scours from either virus at any age. Colostral immunoglobulins usually prevent signs of diarrhea until the antibodies disappear from the intestine at about day 7.
Some Salmonella strains, such as S. typhimurium and S. dublin, are becoming more prevalent. S. typhimurium is found in calves over 10 days of age and causes an intractable disease along with scours, that is difficult to successfully treat and cure. S. dublin may or may not be associated with diarrhea but will lead to systemic disease, high death loss and the development of chronic carriers. Additional strains are becoming prevalent in adults and will no doubt soon be found in calves. Salmonella is also becoming more prevalent in adult cows and has the potential for high mortality rates.
Clostridium perfringins type C causes acute fatal hemorrhagic enteritis in calves less than 2 weeks of age. The largest, healthiest calves are affected and death is usually so rapid that scours or other signs of disease are not usually observed. Cryptosporidia can cause diarrhea at any age but most commonly at 12 to 35 days of age, with oocyst shedding commonly reaching their maximum at about 12 days of age. Likewise, coccidiosis can cause clinically apparent disease at any age but oocyst shedding and diagnosis is difficult until day 21.
This is a brief synopsis of the common calfhood diseases being dealt with today. Proper nutrition, especially adequate colostrum at birth, will help to curb the occurrence of these illnesses. If you have questions about symptoms or diseases your calves are experiencing, ask your ANC consultant or veterinarian for advice.
